Treatment of nonwoven cellulosic fabrics with urea resin colloids



wov'en cellulosic fabrics.

relates to a method for increasing the tensile, strength of non-wovencellulosic fabrics wherein" substantially all the fibers are oriented inone" Patented Nov. 11, 1952 UNITED STATES. PATENT OFFICE TREATMENT OFNONWOVEN CELLULOSIC FABRICS WITH UREA RESIN COLLOIDS James K.Dixonyltivrside, Conn., assignor to American Cyanamid Company, New York,N. Y., a corporation of Maine No Drawing. Application October 26, 1949,

7 Serial N0. 123,793

1 Claim. (cum-e5) This invention relates to the treatment ofnondirection. V

I haverecently discovered that the application of cationicaminotriazine-aldehyde resin acid colloids such as, for example, anacetic acid col: 1016. of methylated trimethylol melamine, to 'un-"woven cellulosic fabrics increases their tensile j strength. Processesfor so treating unwoven cellulosic fabrics are described and claimed inmy copending applications; Serial No. 123,792 filed October 2 6,1949,'entitled Treatment of Non- Woven Cellulosic Fabrics with Weak AcidAminotriazineResin Colloids, and Serial No. 123,795

filed October 26, 1949, entitled Treatment of Non-Woven CellulosicFabrics with Modified Acid Resin Colloids, and now abandoned.

a It is an object of the present invention to provide a process fortreating non-woven cellu losic fabricswherein the fibers aresubstantially all oriented in one direction.

It is another object of the present invention to provide a process fortreating non-wovencotton fabric in which substantially all of the cottonfibers are oriented in one direction.

Another object oi the present invention is to provide a process fortreating non-woven viscose fabric in which substantially all of theviscose fibers are oriented in one direction.

Still another object of the present invention is to provide a processfor the treatment of nonwoven fabrics containing a mixture of cotton jMore particularly, it

and viscose fibers substantially all of which are oriented in a singledirection. 7

A further object of the present invention is the production of anon-woven cellulosic fabric of increased tensile strength.

It is a further object of the present invention to increase the. tensilestrength of non-woven cellulosic fabrics in which substantially all ofthe fibers are oriented in one direction, the increase occurring both inthe direction of the fibers and in-the direction perpendicular 'tothat'of the The above and other objects are attained by treating afabric composed of substantially unidirectionally oriented, non-wovencellulosic fibers with a colloidal aqueous solution of a polymerizedaldehyde condensation product of a carbamido.

compound such as urea.

The invention will be described in greater detail in conjunction withthe following specific examples in which proportions are given in partsby weight unless otherwise noted. The examples are merely illustrativeand it is not intended that the scope of the invention be limited by thedetails therein set forth.

EXAMPLE 1 A non-woven fabric known as cotton Masslinn is used in thisand certain of the following examples. The cotton fibers in Masslinn aresubstantially all oriented in one direction, and the parallelized fibersare bonded together at intervals in a direction perpendicular to thedirection of the fibers with a thermoplastic resin of the polyvinylacetate type, the resin constituting generally from about 6%-10% of theweight of the fabric. Although the tensile strength of Masslinn willdepend to a degree upon the way in which it is mechanically processed ortreated, it will be Resin Designation Resin Description ResinA Aceticacid colloid of ammonia modified I urea-formaldehyde resin. Resin BTetraethylenepentamine mo difi e 1 urea R C formaldehyde resin colloid.

65111 Bicsllligtg modified urea-formaldehyde resin The wetted outsamples are i Tensile Strength Percent m Resin Add on Warp Fill It isbelieved that the resin colloid solution extracts and/or redistributesthe polyvinyl-acetateresin binder present in Mas'slinn This theory seemsto be borne out by the fact, as will be demonstrated in a laterexample,'that-'when new woven fabric containing no resin binder is simiflarly treated with a resin colloid solution there appears to be a linearrelationshipbetween resin pick-up and increased tensile strength.Furtheremore it is believed to explain the slight apparent decreases inwarp tensile strength which'are sometimes observed. In SliCh instances,however, there. is;.an over-alt increasei in tensilestrength sinczthatin the fill direction increases propertion'ately" far' more' thanrthafiJOff the warp may decrease.

Similar treatment ofi Massli'nn: with-' non col- 1oidal2- dimethylol:urea and an; acid-liberating... catalysts decreases: the tensilestrength: of the:- :Eabtic:

In this example a non-woven cotton' mate-- rial composed ofsubstantially unidirectionally oriented fibers with-nrrresirr binder isused instead of Masslinn. Since the material has very little tensilestrength in the dry state and even less}- when wet, it may be desirableto support itduring..--the; application of; resin thereto;

Samples of the: nonwoven material aresupported? on sheets. oftin; platedsoft steel 0-.012- inch; thick having a smooth. surfaceeand resincolleid-;-solutions are carefully poured thereover; Thetin.sheets withthe so wetted out-t-samples are then passed threugh. squeeze: rollsasin- Example l. The materia lis stripped; from the-sheets-andq cured byheating. for about fi-lo'minutesl at: about. 140 C.

The: result of: tensile strengthmeasurements; name. samples.off-treated: material are set forth in the. following' tablez 1 TensilePercent Resinv Strengthen 'lbstlfill as, for example, by glacial aceticacid, are treat- 75 5 minutes.

4 ed as described in the foregoing examples with urea resin colloids.

Preparation of resin A 60 parts urea (1 mol) 243 parts 37% aqueousformaldehyde (3 mols) 38.5 parts ammonium acetate (0.5 mol) Theformaldehyde is adjusted to a pH of about 8.5, the urea is dissolvedtherein, and the solution is heated at'70- C. forlflminute's; Theammonium acetate is then added,-and the reaction mixture is heated toboiling and boiled gently for A noticeable viscosity increase occurs.The cationic resin colloidal solution obtained contains 3 l'%- resinsolids.

Preparation of resin B 0'-.'7'5-part trietha-nolamine 20.0 parts urea2-.ojparts tetraethylenepentamine 2.8 parts hydrochloric acid (specificgravity 1.19) 7.l parts water 4.4 parts 10% aqueous sodium hydroxide Theformaldehyde andtriethanolamiiie are charged into a kettle and wellstirred. The urea is added and aftermixing the-solution, which has a'pHof about 9;6-8:8, heated by s'tearjnby 3' parts of wa'te'rljThetemperature-rises my about C. 'duringthisad'dition due to the heat--andasolution of' the hydrochloric "acid in 3 1 parts ofwater is added;The remaining Water is'also added. The temperatureiof thereaction" isagain brought to about 70"-' C; andmaintained at that temperature forone hour. Te'n' minutes'a'fte'r the addition of tlie'. acid,the"pI-I'1of the mixture is.

about 2.4 and it gradually} drops to. 1.7 -1.81" Aft er the hourreactiontli'e reaction'productis cooled downv by cooling watentb; 55 C.and immediately neutralized by slowjaiddition of the sodiumhydroxidesolution. After. further coolingito about 20-25" C. thei'p'H ofther'esin i'sadjusted to 618 7.0. The resin: syrup obtainedin" whielrthemolar ratio of'formaldehyde to ureais 2.5-:1

contains about 45% man solids." This ane-ebased only" on theresin-forming "ingredients and ignores salts and minorringredient's;

Preparation of resin 6 7175; parts. 37%; aeueaus tormaldehyd 40.5; partssod'iuni-.mtabis'ul'fite' 236"par.tsfurea j 2.8 parts 10% aqueous'seaium'Hydroxide: 1.1 parts 36% hydrochloricacid 2.2 partstriethanolamine.

The sodium metabisulfitei-andl urear are dise solved in the formalin andthe' pH of the somtibii isadjusted mea ae byithe addition; ofithe:sodium hydroxide solution; The-mixture 'isfhea-te ed torefiux andrefiux'edsfor thirtyminutesa: Hy-' droc'hloric acid is theniaddeditolower" the": pH

of the's'oluti'on at 310-315". In'order to compensate: for the heat ofdilution of the acid it is adviser ble t'o. coolv the: solution-to about80 C; before the acidi is added}: The'reaction mixture is 11r-- therrefluxed for one hour, cooled to -85 C.

As the reaction is exothermic'some' and maintained at that temperature.The visc'osity of the resin syrup will increase steadily and when itreaches around 200 centipoises measured by the Gardner-Holdt method thereaction is stopped by addition of the triethanolamine. The resin iscooled to room temperature and additional triethanolamine is added ifnecessary to adjust the pH to 8.0-8.5.

-:.\The resin solution in' which the formaldehydeurea mol ratio is2.25:1 contains about 54% resin solids. This figure is based onthe-resin-forming ingredients including the sodium metabisulfite anddoes not include salts and minor ingredients. w

In general, whenever the monomer of a carbamide-aldehyde resin can beconverted to a polymer which lends itself to the formation of acolloidal solution of the polymerized resin, the resin is found toimpart an appreciable improvement in the tensile strength of non-wovencellulosic fabrics, both in the direction of the fiber and in thedirection perpendicular to that of the fiber. Most of the resins which Ihave found useful are cationic in nature and since these appear toeifect the largest increase in tensile strength they constitute thepreferred embodiment of my invention. However, anionic type resins(Example 1, resin 0) are also useful.

In addition toResin B, other alkylene polyamine modified carbamideresins such as those modified with ethylene diamine, diethylenetriamine, triethylene tetramine, etc., may be used.

. Moreover, colloidal solutions of guanidine modified carbamide resins,pyridine modified carbamide resins, carbamide resins modified withglycols, amino alcohols, etc., are also useful.

Suitably modified aldehyde condensation products of carbamides includingurea, thiourea, N- hydrocarbon substituted ureas and thioureas such as N-methyl urea, N-phenyl urea, N-benzyl urea, N-ethyl thiourea, N-phenylthiourea, N- benzyl thiourea, etc., wherein each amino nitrogen atomcontains at least one hydrogen atom attached thereto are contemplated ascoming within the scope of the present invention.

Carbamide resins modified with amino sulfonic acids such as sulfanilicacid or with aminocarboxylic acids such as fi-alanine or withhydroxycarboxylic acids such as salicyclic acid may be substituted forthe bisulfite modified resin C.

The aboveresins are prepared by known methods as illustrated by thepreparations of resins A, B and C set forth in detail.

Aldehydes other than the formaldehyde of the examples, such asformaldehyde-yielding materials including paraformaldehyde andhexamethlyenetetramine, benzaldehyde, furfural, acetaldehyde,paraldehyde, etc., may be used.

Resin colloids containing hydrochloric or other strong acid may not beused in the process of the present invention since they do not improvethe tensile strength of the non-woven cellulosic fabrics.

In order to obtain the optimum effect of the present invention, thenon-woven cellulosic fabricis so treated with the acid resin colloidsthat from about 0.5% to 25% by weight of resin solids, based on the dryweight of the fabric, will be deposited therein. Actually there is noreal lower limit since incorporation of any small amount of,

the resin will increase the tensile strength to some degree but forpractical purposes a lower pick-up than 0.5% will not increase thetensile strength appreciably. Higher pick-ups than 25%, however, produceundesirable properties such as excessive stiffness and harsh feel, andaccordingly the upper limit is a real and practical one. I i

The invention is not limited to any particular method offimpregnation ofthe non-woven fabric which may be immersed in a resin solution and theexcess resin removed or which may be sprayed with a resin solution ifnecessary. or if desired. In any event special care in handling must betaken in view of the. extremely low tensile strength of the untreatednon-woven fabrics, particularly when they are wet. I, In the examplesthe resin-impregnated fabrics are dried and cured at about 140 C. forfrom 6-10 minutes. This is merely a matter of convenience since theacidcolloid produces thesame tensile strength increase at much lowercuring temperatures. Even air drying is suiiicient, and therefore littleor no heat curing is really necessary in order to obtain in the fabric aresin polymer with desirable binding properties. Generally speaking,however, the impregnated fabric will be allowed to dry at temperaturesranging from about 65-400 F.

Non-woven fabrics composed of substantially unidirectionally orientedcellulosic fibers, when treated according to the process of the presentinvention, are likely to possess a harsh and somewhat stiif hand, thiseffect being dependent upon the resin concentration and increasing withincreased add-on or dry pick-up of the resin. There are several ways ofimproving the appearance and hand of the fabric.

In the first place, the acid colloid resins may be printed ontonon-woven fabrics in much the same manner as the manufacturers ofMasslinn apply the resin binder.

Another method involves lap calendering of dried non-woven fabricstreated with the resin colloids to: soften the hand.

Moreover, the resin colloid treated non-woven fabrics may be hotcalendered. A soft, yet firm, v

hand results.

A fourth remedy involves addition to the resin colloid of a textilesoftener such as, for example, the reaction product of from 5.5-6.5 molsof ethylene oxide with one mol of a mixture of the octadecylamine saltof N-octadecyl carbamic acid and the octadecyl guanidine salt ofN-octadecyl carbamic acid as described in U. S. Patent No. 2,427,242.The softening agent appears to make the surface feel less harsh.

It is an advantage of the present invention that non-woven fabric whichhas been treated with a resin colloid may be dyed or pigment printed.Moreover, the treatment of the present process animalizes the fabric sothat it may be dyed with acid dyestuffs.

The treated fabrics of the present invention may :be coated to obtaininteresting and useful articles. Other uses for my resin treatednonwoven fabrics are as folows: towels, napkins, doilies, dish cloths,table cloths, drapery materials, wall covering, pipe covering, milkfilters, cheese press cloths, ribbon, chemical filters, etc. If they areheat pressed to a stiffness, the fabrics are useful in the manufactureof lampshades, lintless wiping cloths, etc.

Use of my resin colloid treated non-woven fabrics as the plies of alaminate results in the production, of a laminated product of improvedfiexural strength, flexural modulus, hardness and tensile strength anddecreased water absorbency when compared with one made up of plies ofuntreated non-woven fabric.

wer mm I ALDIOCGSSWhiChT consists-- of immersing: 92211011?" wovenfabric composed of substantially unid1:-

rotationally orientedootton' and; viscosezfibers" in eqiml proportionsdna; neutral. colloidal aqueous; solutioni off ai-cationiai'po'lymerizedmodifidmreai fovmafidehyde condensation productzprepared; by reaiotm'gi6718' parts df formalim 20: parts: of:- urea; fiil t'sby'weightofltetraiethylnepnfimmn' "e1:

uni a'eidi conditions for more: than?" 11/; hours .10 at '70 dgr'ees'centi'zmd 'and then neutralizing;

the reaction proflmxniemzttor squeezing; the

afiidwint of condensation prodilct on the fabrid.

to I3 percent: of the div weight of fabric); the'r 'e v Mais-substantiallyincreased;

and; 10'? minutes 1- dry: ihei-= fazbrim andjcllrewthev'condensatiom-producm to; a; :water -ins olublor sum.

and-dap' acalenderi-ngith'evdnied fabrica-tozsoitnzthe hand-:wherebythvfill tensile-stnengthoiithafiabfi Number Name Dato. l

